Cooking apparatus of the type disclosed in U.S. Pat. No. 3,884,213, entitled "Cooking Apparatus" which issued May 20, 1975 to Donald Paul Smith, directed jets of temperature controlled gaseous fluids to impinge against irregularly shaped food products to subject discrete areas on the surface of the food product to a very high heat transfer rate. The subareas subjected to the high heat transfer rate were moved over the surface of the product to obtain desired overall surface effects such as crisping, browning, searing or freezing. Impingement ovens made in accordance with the teachings of U.S. Pat. No. 3,884,213 are commercially available from Enersyst Development Center, Inc. of Dallas, Tex., under its registered trademark "JET SWEEP" and from its licensees, Lincoln Foodservice Products, Inc. of Fort Wayne, Ind., under its registered trademark "IMPINGER"; Middleby Marshall, Inc. of Morton Grove, Ill., under its registered trademark "PACE SETTER"; and Fujimak Corporation of Tokyo, Japan. "JET SWEEP", "IMPINGER" and "PACE SETTER" ovens have enjoyed extensive commercial success, particularly for cooking pizzas.
The heat transfer apparatus disclosed herein relates to improvements in devices of the type disclosed in U.S. Pat. No. 4,154,861, entitled "Heat Treatment of Food Products"; U.S. Pat. No. 4,338,911, entitled "Cooking Apparatus"; U.S. Pat. No. 4,377,109, entitled "Apparatus for Baking Food Products Such as Pizzas"; U.S. Pat. No. 4,479,776, entitled "Thermal Treatment of Food Products"; U.S. Pat. No. 4,492,839, entitled "Thermal Treatment Apparatus"; U.S. Pat. No. 4,523,391, entitled "High Efficiency Impingement Heating and Cooling Apparatus"; U.S. Pat. No. 4,679,542 entitled "Fan-Plenum Configuration"; U.S. Pat. No. 4,462,383, entitled "Impingement Food Preparation Apparatus"; U.S. Pat. No. 4,474,498, entitled "Multiple-Pass Impingement Heating and Cooling Device"; and U.S. Pat. No. 4,757,800 entitled "Air Flow System for A Low Profile Impingement Oven."
These patents disclose improvements in cooking apparatus of the type disclosed in U.S. Pat. No. 3,884,213 and generally relate to a variety of structures for improving air flow to and from irregular-shaped food products for increasing cooking efficiency.
U.S. Pat. No. 3,884,213 disclosed a cooking apparatus in which a pizza or other food product was supported on a carriage. The carriage reciprocated between upper and lower jet plates which formed and projected spaced jets of heated air toward upper and lower surfaces of the food product. Passages in the jet plate were spaced such that spent air from the jets, after impinged against upper and lower surfaces of the food product, was drawn between the spaced air jets enroute to an intake opening to an impeller which circulated the air. A second embodiment disclosed in Smith U.S. Pat. No. 3,884,213 incorporated a stationary food support in which the jet plate was moved for causing the point at which the air jets impinged on the food product to move relative to the food product.
In microwave ovens, food products have been supported on turntables rotating between upper and lower jet plates of the type disclosed in Smith U.S. Pat. No. 3,884,213. The ovens were similar to that disclosed in Smith U.S. Pat. No. 3,884,213 except that the food product was supported on a rotating turntable.
Bingham U.S. Pat. No. 4,924,763, issued May 15, 1990, entitled "Compact Pizza Oven", is assigned to Pizza Hut of Wichita, Kans., and discloses an oven in which a turntable supports a pizza rotated about its center while heated air is delivered through top and bottom slots toward upper and lower surfaces of the pizza as the turntable rotates. The slots are disclosed as having midpoints above and below the center of the turntable and a length substantially equal to the diameter of the turntable. An oven door is hinged on one vertical side of the oven and the turntable, which is connected to the door. The turntable is driven by a motor located on the door and is brought out of a baking chamber when the door is swung open.
Pizza Hut U.S. Pat. No. 4,924,763 summarizes the history of pizza ovens which has evolved from the use of deck ovens requiring a bake time between 15 and 25 minutes per pizza to modern impingement ovens of the type disclosed in U.S. Pat. No. 4,679,542 issued to Don Paul Smith having a typical bake time in a range of 5 to 9 minutes.